Magpul BAD Lever - Definitely Recommend It
I'm surprised no one has reviewed this on here yet. There are hundreds of 5 star reviews on the web. It's as useful as an enhanced magazine catch button. You don't have to change your grip, and I find it especially useful for manually locking the bolt open. If you have a Gucci milled lower reciever it may not fit, but if you have a bog-standard forged mil-spec reciever, you will have no interference issues. I have never had a problem with any of the four different lowers I have used it on. Some reviews have complained about wiggle, but in my experience, the wiggle is in the bolt catch button in the reciever. The B.A.D. Lever just makes it more noticeable.